C2h4 + o2 → 2c + 2h2o mg + h2o → mgo + h2 n2 + 2o2 → 2no2 s + o2 → s + h2o
which of the following is a valid combustion reaction?

N₂ + 2O₂ → 2NO₂

Explanation:A combustion reaction in which substances burn completely or partially in presence of oxygen gas.In this case the valid combustion reaction is;

      N₂(g) + 2O₂(g) → 2NO₂(g)

The reaction shows the combustion of nitrogen gas in air to produce nitrogen (IV) oxide.Other type of chemical reactions include precipitation reactions, decomposition reactions, synthesis reactions, single and double replacement reactions among others.